The present invention relates to a collet and seat assembly, and more particularly, to a push-type collet and seat assembly which enables a workpiece to be machined to a precise length without the need for a "facing" cut.
The use of a conventional pull-type collet for positioning stock (for example, a workpiece such as a rod or tube) is well-known in the cutting art. It is acceptable as long as it is recognized that a "facing cut" must be made if the stock is to be machined to a precise length. The facing cut is required because the collet draws the stock backwards as the collet is being tightened. The amount of drawback is not controllable where even small variations of the diameter of the stock being positioned are to be expected as even a small variation in the diameter will vary the exact instant at which the collet initially grasps and finally immobilizes the stock against longitudinal motion relative to the collet.
It is also known to use a conventional "dead length" collet. The dead length collet differs from the pull-type collet by closing upon the stock in a vertical, transverse and radial direction. Where the stock is to be machined to a precise length, it is recognized that a facing cut must be employed as no pressure is exerted by the stock against the stop as the collet is being tightened. As it cannot be expected that the surface of the stock being positioned will be totally clean and devoid of irregularities, the absence of any pressure exerted by the stock against the stop introduces an uncertainty factor. This uncertainty factor would be greatly reduced or eliminated if the stock were to exert pressure against the stop while the collet is being tightened as this would minimize or eliminate the effects of such irregularities.
Accordingly, it is an object of the present invention to provide a collet and seat assembly which will enable a workpiece to be machined to a precise length without the need for a "facing" cut.
Another object is to provide such an assembly which employs a push-type collet.
A further object is to provide such an assembly which minimizes the effects of minute projections on the forward end of the stock by forcing the stock against a stop.
It is also an object of the present invention to provide such an assembly which is simple and inexpensive to manufacture and economical and easy to use and maintain.